Thorad SLV-2A Agena D

The Thor missile program was initiated in December 1954, when USAF headquarters issued requirement for a tactical missile intended to travel a distance of between 1 150 and 2 300 miles. Thor was undertaken as a high-risk program having the goal of achieving flight within the shortest possible time. The Thor had its first complete launch pad test in January 1957 and a full-range flight test in September 1957.
The Thor-Agena D was first used on 28 June 1962 to launch a classified Air Force payload from Western Test Range. The lift capability of the vehicle was significantly increased when the new model DSV-2C, or Thrust Augmented Thor, was introduced into the launch system on 28 February 1963. That Thor configuration incorporated 3 solid-propellant motors which dropped off after burnout.
The OGO (Orbiting Geophysical Observatory) spacecrafts were designed for NASA's Goddard Space Flight Center by TRW to conduct correlated investigations of geophysical and solar phenomena in the earth's atmosphere and magnetosphere and in interplanetary space. OGO 4 was launched by Thor Agena D (TA-8) on 28 July 1967. It was the second succesfull OGO carried 20 experiments, including 10 from 9 universities, one from Australia and 5 from NASA's Jet Propulsion Laboratory.